EP0090731B1 - Regulating and controlling device for an actuating cable for drum brakes, and drum brake incorporating such a regulating device - Google Patents

Description

The subject of the invention is a device for adjusting and controlling a control cable for a drum brake and a drum brake incorporating such an adjusting device, in particular for a motor vehicle.

The invention generally relates to a drum brake comprising two segments elastically biased in abutment at one of their ends against an anchor block and actuated at their end by a brake motor. A handbrake lever pivotally mounted on one of said segments is capable of applying the brake under the action of a handbrake cable associated with the free end of the lever.

On drum brakes of this type, it is often difficult to ensure a correct adjustment of the tension of the handbrake cable, that is to say that the cable is insufficiently tensioned and in this case a dead stroke appears on the cable, this stroke dead could be incompatible with the travel available to the handbrake lever located in the cabin, or that the cable is over-adjusted, the tension is then such that the handbrake lever already biases the segments apart and can cause the clamping of the brake.

We tried to solve this problem by making a device which allows to check the adjustment of the cable or in case of over-adjustment of the wear take-up device to be able to release the brake by allowing the segments to approach (see in particular the English patent filed March 1, 1969 and published under No. 1,247,245). In this patent, it is proposed to add vis-à-vis the free end of the handbrake lever a removable stop which allows during its extraction to bring the two segments together; in this same patent, it is proposed to introduce inside the stopper a plunger axially displaceable and making it possible to control the position of the handbrake lever by measuring the stroke of the plunger between the position of the plunger pulled outwards brake and push button on the hand brake lever.

This device effectively verifies that the cable adjustment is correct; however, it has two major drawbacks. On the one hand, when the handbrake is actuated, the lever moves away from the device, the plunger can then penetrate further into the stop and prevent the lever from returning to its place when the action on the cable is removed. On the other hand, the sliding of the two parts of the device on the one hand relative to the other can be prevented, the part of this device external to the brake being in an area subjected to projections from the road and liable to be fouled; the device can become inoperative or prevent the lever from receding and therefore generate parasitic braking of the brake. The same document proposes to add a third part ensuring anti-pollution protection. However, this solution has the drawback of prohibiting significant movement of the plunger and therefore may not allow contact between the plunger and the handbrake lever and therefore of prohibiting control of the position of the latter.

To avoid these drawbacks, the invention provides a device for adjusting and controlling a control cable for a drum brake comprising a lever pivotally mounted by one of its ends on a segment of said brake and capable of applying brake under the action control cable connected to the other end of said lever, said adjustment and control device consisting of a stop member passing through an orifice formed in a support plate and having a portion placed opposite from the other end of said lever, said device being capable of passing from a first so-called rest position to a second predetermined position called control, characterized in that an erasable stop keeps said device in the rest position.

As will be seen more precisely in the description which follows, the invention makes it possible to produce an adjustment and control device in one piece, which does not risk blocking the handbrake lever, and which does not risk by fouling to prohibit the control of the adjustment of the control cable.

• - la Fig. 1 est une vue de face d'un frein à tambour comportant le dispositif de réglage réalisé conformément à l'invention;
• - la Fig. 2 est une vue en coupe du frein de la Fig. 1 suivant la ligne 11-11 de la Fig. 1 ;
• - la Fig. 3 est une vue agrandie en coupe partielle du dispositif de réglage représenté sur la Fig. 2 avant son montage dans le frein;
• - la Fig. 4 est une vue dans le sens de la flèche B du dispositif de la Fig. 3;
• - la Fig. 5 est une vue agrandie en coupe suivant la ligne V-V de la Fig. 6 du dispositif de réglage réalisé conformément à l'invention selon un deuxieme mode de réalisation; et
• - la Fig. 6 est une vue dans le sens de la flèche C du dispositif représenté sur la Fig. 5.

Two embodiments of the invention will be described by way of non-limiting examples with reference to the appended figures in which:

• - Fig. 1 is a front view of a drum brake comprising the adjustment device produced in accordance with the invention;
• - Fig. 2 is a sectional view of the brake of FIG. 1 along line 11-11 of FIG. 1;
• - Fig. 3 is an enlarged view in partial section of the adjustment device shown in FIG. 2 before mounting in the brake;
• - Fig. 4 is a view in the direction of arrow B of the device of FIG. 3;
• - Fig. 5 is an enlarged sectional view along the line VV of FIG. 6 of the adjustment device produced in accordance with the invention according to a second embodiment; and
• - Fig. 6 is a view in the direction of arrow C of the device shown in FIG. 5.

The drum brake shown in Figs. 1 and 2 comprises a support plate 10 provided for associated with a fixed part of the vehicle (not shown). This support plate 10 slidably receives two segments 12 and 14 comprising on their periphery friction elements 16 and 18, respectively, held on the segments by means of rivets or the like (not shown). The ends 20 and 22, respectively, of the segments 12 and 14 are kept applied to an anchoring block 24 by means of a spring 26. A brake motor designated as a whole by the reference 28 formed, in the embodiment shown, by a hydraulic wheel cylinder is placed between the ends 30 and 32, respectively, of the segments 12 and 14. A spacer 34 is placed between the segments 12 and 14 in the vicinity of the brake motor 28. A handbrake lever 36 is pivotally mounted by one of its ends 37 on the segment 14 by means of a pivot pin 38. The other end 42 of the lever 36 receives the end 44 of a cable hand brake 46 connected by its other end (not shown) to a hand brake lever located in the cabin of the vehicle (not shown). The segments 12 and 14 are urged to bear on the spacer 34 by means of a spring 48 which also urges the hand brake lever 36 in the direction of the arrow A as long as the segment 14 has not found its abutment on the spacer 34.

As can be seen more precisely in FIG. 2, the hand brake lever 36 is supported by its end 42 on an adjustment and control device designated as a whole by the reference 50, this when the cable 46 is not mounted in the brake or when the cable 46 is mounted but completely relaxed. The adjustment and control device 50 passes through a circular orifice 52 formed in the support plate 10 and is placed opposite the free end 42 of the hand brake lever 36.

Referring to FIG. 3 where the adjustment and control device is shown in partial section along line III-III of FIG. 4, it can be seen that this device is formed in one piece comprising a portion 54 capable of receiving the end 42 of the lever 36 in support; this portion 54 ends with a flange 56 forming a lateral projection, this flange coming to bear on the edges of the orifice 52 as shown in FIG. 2. The device 50 comprises a cylindrical part 58 of diameter slightly smaller than the diameter of the orifice 52 formed in the support plate 10 and the length of which is substantially equal to the thickness of the support plate 10. The cylindrical part 58 is extended in the mode represented by four tabs 60, as can be seen more precisely in FIG. 4, each formed by a portion of a truncated cone 61. These tongues end in a projection 62 which limits the risks of untimely dismantling before assembly of the strand and a second portion of truncated cone 64. Each of the tongues 60 bears on its periphery a mark formed by a groove 66 placed at a distance a from the collar 56. As can be seen in FIGS. 3 and 4, the body of the adjustment device 50 has a recess 68 which gives good flexibility to the tongues 60. The tongues 60 are separated from one another by cutouts 70 allowing their relative movement.

Referring to Figs. 5 and 6, in which a second embodiment of the adjustment device of FIGS. 3 and 4, the elements fulfilling similar functions will have the same references increased by 100.

The adjustment device 150 has a first portion 154 on which the handbrake lever 36 can come to bear. The device 150 also includes a flange 156 as well as a cylindrical part 158 with a diameter less than the diameter of l orifice 52 of the support plate 10 and whose length is substantially equal to the thickness of the support plate 10. The device 150 has an extension 192 of a diameter substantially equal to or slightly less than the cylindrical part 158. In the portion 192 are formed two recesses 168 diametrically opposite delimiting two tongues 160 coming integrally with the device 150. The end diameter d of the tongues 160 is of a diameter substantially larger than the diameter of the orifice 52 of the plate support 10. The tongues 160 and the portion 192 have a mark formed by a groove 166 placed at a distance a from the collar 156. As can be seen in FIG. 5, the tongues 160 have good radial flexibility thanks to the recess 168 and to the connection portion 194.

Referring to FIG. 1 it can be seen that the brake is also provided with an automatic wear adjustment device of a type known per se, comprising a lever 72 articulated at one of its ends on the segment 12 by means of an axis forming pivot 74. This lever 72 has at its other end a toothing 76 which cooperates with a toothing 78 formed on a latch 80 pivotally mounted on the segment 12 by means of a pivot axis 82. The latch 80 is rotated by a torsion spring 84 wound around the axis 82 so that the toothing 78 cooperates with the toothing 76. The latch 80 has an opening 86 near the toothing 78. In a manner known per se, the spacer 34 is biased to the right with reference to FIG. 1 by a spring 88. The spacer 34 comprising at its left end with reference to FIG. 1 a projection 90 capable of causing the lever 72 to rotate in an anti-clockwise direction, always with reference to FIG. 1, when the spacer 34 is biased to the right of FIG. 1.

• La plaque support 10 est préalablement équipée du bloc d'ancrage 24 et du moteur de frein 28. On met alors en place le dispositif de réglage 50 dans l'orifice 52 formé dans la plaque support 10. Pour cela, on présente le dispositif 50 en face de l'orifice 52 suivant la flèche D de la Fig. 2. La portion troncônique 64 pénètre partiellement dans l'ouverture 52 et par poussée axiale dans le sens de la flèche D, les languettes 60 vont fléchir radialement vers l'intérieur de façon à permettre le passage des saillies 62 au travers de l'orifice 52. En maintenant l'effort dans le sens de la flèche D, le dispositif 50 pénétrera davantage dans l'ouverture 52 jusqu'à ce que la collerette 56 vienne en appui sur les bords de l'ouverture 52; les languettes 60 auront alors repris leur position libre telle que représentée sur la Fig. 3, la portion troncônique 61 formée par les languettes 60 empêchant le mouvement du dispositif 50 dans le sens inverse de la flèche D. En effet, les bords de l'ouverture 52 interfèrent avec le tronc de cône 61 formé par les languettes et un effort dans le sens inverse de la flèche D serait nécessaire pour faire fléchir les languettes 60 radialement vers l'intérieur et permettre ainsi le mouvement du dispositif 50 dans le sens inverse de la flèche D. On procède alors au montage des autres éléments du frein, c'est-à-dire les segments préalablement équipés d'une part de levier de frein à main et d'autre part du dispositif de réglage automatique d'usure. Avant mise en place des ressorts 26 et 48, on procède à la mise en place de l'entretoise 34 entre les deux segments 12 et 14 avec le ressort 88 associé à cette entretoise.

The adjustment device and the brake which have just been described are mounted as follows:

• The support plate 10 is previously equipped with the anchoring block 24 and the brake motor 28. The adjustment device 50 is then put in place in the orifice 52 formed in the support plate 10. For this, the device 50 is presented. opposite the orifice 52 according to arrow D in FIG. 2. The frusto-conical portion 64 partially penetrates into the opening 52 and by axial thrust in the direction of the arrow D, the tongues 60 will flex radially inwards so as to allow the projections 62 to pass through the orifice 52. Maintaining the force in the direction of arrow D, the device 50 will penetrate further into the opening 52 until the flange 56 comes to bear on the edges of the opening 52; the tongues 60 will then have returned to their free position as shown in FIG. 3, the frusto-conical portion 61 formed by the tongues 60 preventing movement of the device 50 in the opposite direction to the arrow D. In fact, the edges of the opening 52 interfere with the truncated cone 61 formed by the tongues and an effort in the opposite direction of arrow D would be required to flex the tongues 60 radially inwardly and thus allow the movement of the device 50 in the opposite direction to the arrow D. The assembly then takes place of the other elements of the brake, that is to say the segments previously equipped with '' a handbrake lever part and the automatic wear adjustment device on the other hand. Before the springs 26 and 48 are put in place, the spacer 34 is inserted between the two segments 12 and 14 with the spring 88 associated with this spacer.

Then the hand brake cable 46 is put in place as shown in FIGS. 1 and 2, the cable not being stretched.

The cable tension is then adjusted, adjustment takes place using a screw-nut device for example (not shown) placed on the cable path between the brake and the vehicle cabin (not shown). ). The tension which appears on the cable tends to move the handbrake lever 36 to the left with reference to FIG. 2. During the adjustment of the cable, the operator holds between his fingers the tongues 60 which he compresses radially inwards so that the frusto-conical portion 61 formed by these tongues is comparable to a cylinder. The operator is then able to axially move the device 50 in the opposite direction to the arrow D (see FIG. 2) until the outer edge of the opening 52 comes opposite the groove 66 formed on the tongues 60. The cable tension is then correct. The operator then pulls on the tongues 60 so that the device 50 and, more particularly the collar 56, again comes to bear on the edge of the opening 52 and this in the direction of the arrow D in FIG. . 2. The truncated cone 61 formed by the tongues 60 prohibits the device 50 from following the movements of the hand brake lever 36.

The mounting of the adjustment device 150 is carried out in a similar manner to the mounting of the device 50. The connection portion 194 as well as the portion 192 are presented in front of the orifice 52 in the direction of the arrow D. A directed force in this same direction D applied to the partition 154 makes it possible to introduce the device 150 into the orifice 52 axial thrust, the tabs 160 being bent radially inward so as to allow the introduction of the device into said orifice 52. When the collar 156 has come to bear on the edges of the orifice 52 the tabs 160 are released from the orifice 52 and are placed facing the external edges of the orifice 52, thus preventing the device 150 to move in the opposite direction to the arrow D shown in FIG. 2. The rest of the brake is assembled in the same way as described above. When we want to adjust the cable tension, the operator bends the two tabs 160 so that they can enter the opening 52. The operator can then move the device 150 in the direction reverse of arrow D so as to follow the lever movement 36 and stop adjusting the handbrake cable 46 when the grooves 166 formed on the tongues 160 have reached the external face of the support plate 10.

In the two embodiments, the grooves 66 and 166 are placed at a distance a from the flange 56, this distance corresponding to the movement of the lever 36 to obtain a good increased adjustment of the thickness of the support plate.

If an over-adjustment of the brake occurs, it is not necessary to remove the adjustment device 50 or 150 to ensure the approximation of the segments. In a manner known per se, by means of the opening 86 carried by the latch 80, it is possible to rotate the latter in the clockwise direction with reference to FIG. 1, so as to disengage the toothing 78 from the toothing 76, the automatic adjustment device then becoming inoperative, the two segments come together. This system makes it possible not to destroy or damage the adjustment devices 50 or 150 to obtain this result.

It therefore appears from the foregoing description that, on the one hand, the adjustment and control device is effectively immobilized by the tongues in the so-called rest position and that, on the other hand, there is no risk of device malfunction. In fact, if the surface of the frusto-conical area is covered with mud, the operator will bend the tongues a little more to allow passage through the orifice and cleaning the surface of the tongues with the edge of the orifice, the mud having the possibility of being released either towards the outside or towards the inside of the device through the cutouts and recesses made between the tongues.

The shapes of the handbrake lever or the tabs can be changed.

The invention also applies to brakes having an automatic adjustment device different from that shown in FIG. 1 or even without any automatic adjustment.

Claims (8)

1. A regulating and controlling device for an actuating cable for a drum brake, comprising a lever (36) pivotally mounted by one of its ends (37) on a segment (14) of the brake and adapted to actuate said brake under the action of an actuating cable (46) connected to the other end (42) of said lever (36), said regulating and controlling device (50, 150) comprising a stop element traversing an orifice (52) formed in a support plate (10) and comprising a portion (54, 154) disposed adjacent the other end (42) of said lever (36), said device (50, 150) being adapted to move from a first or rest position to a predetermined second or control position, characterized in that a removable abutment (60, 160) retains said device (50,150) in the rest position.

2. The regulating and controlling device (50, 150) of claim 1, characterized in that said rest position is defined by an axial abutment of lateral projections (56, 156) integral with said device on the edges of said orifice (52) formed in said support plate (10).

3. The regulating and controlling device (50) of claim 2, characterized in that said orifice (52) is circularand inthatsaid removable abutment (60) is formed by a conical zone (61) formed on said device (50), the smallest diameter of which is smallerthan the diameterof said orific (52) and the greatest diameter of which is greater than the diameter of said orifice (52), said smallest diameter being disposed closeto said orifice (52).

4. The regulating and controlling device of claim 3, characterized in that said conical zone (61) is formed by a plurality of tongues (60) integral at their one ends with said device (50) and adapted to be resiliently deflected in a radial sense.

5. The regulating and controlling device (150) of claim 2, characterized in that said removable abutment (160) is formed by a plurality of tongues (160) integral at their one ends with said device (150), while their other ends adjacent the edges of said orifice (52) are adapted to be deflected in order to enter said orifice (52).

6. The regulating and controlling device (50, 150) according to any of the preceding claims, characterized in that said device is a one-piece member, with said removable abutment (60,160) being made of the material of said one-piece member.

7. A drum brake including a regulating and controlling device (50, 150) according to any of the preceding claims, characterized in that when said lever (36) is not biased by said cable (46), said lever (36) is normally in abutment with said device (50,150).

8. The drum brake of claim 7 in connection with claim 4 or claim 5, characterized in that said regulating and controlling device (50,150) comprises a mark (66, 166) provided on said tongues (60, 160) and spaced from said support plate (10), the distance from said support plate (10) defining said predetermined second orcontrol position.

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